August 19 – The last bit of the fieldwork puzzle is coming together as the aerial survey started yesterday, adding yet another and final aspect to the list of narwhal related research in Scoresby Sound.
The company where we charter the Twin Otter airplane is based in Akureyri, Iceland and we spend the first day installing the recording equipment in the plane. Yes, it takes a whole day. The plane needs bubble windows so the observers can look directly under the plane, making sure that animals close to the plane are detected. We also have a communication system, a video camera, a custom-build GPS tracking system and a recording device that we invented together with Icelandic colleagues called a geometer. It works this way: observers detect a whale, they then press a button on the geometer that records and log the declination angle to the whale. Since we fly at a fixed altitude (700 feet), using simple geometry will give us the distance to the whale. After the survey is completed, we will have a frequency of distances, with more observations at shorter distance to the plane’s track line. These distances help us model the detection function for the observers that give us an idea on how many whales the observers see. This “distance sampling” technique is essential for estimating abundance of wildlife in large areas. By using 2 observers in either side of the plane, we can also calculate the perception bias, i.e. how many whales are missed by the front or rear observer. Finally, we account for availability bias, i.e. some whales are unavailable to the observers because they are below the water surface as the plane overfly. We use the percentage of time the whales spend at the surface with measurements from narwhals tagged with satellite transmitters in previous years in Hjørnedal.
After testing the equipment, we are off towards Scoresby Sound. We start the survey in Gåsefjord where we know we have to look out for “Paamiut”. And there, after a few kilometres flown, we spot the ship going into the fiord. Eva is standing in the front taking a picture of the plane while I take a picture of the ship and her – a reflective moment between two colleagues at two different platforms in the middle of Scoresby Sound.
Not long after, we detect a group of narwhals. The whales move slowly through the water, some in pairs, others alone, and we even spot a mother with a newborn and an older calf and we count approximately 30 whales in total. They seem to just be hanging around in this small bay close to a calving glacier filling up the bay with icebergs. Since narwhals tend to spend most of their time close to calving glaciers we make sure to take pictures of all glaciers in the fiord. Well, the pilots take pictures – the observers are busy searching for whales.
Finalizing the planned transects in Gåsefjord we leave for Constable Point making sure we land there while the airfield is open. We unpack, look at the muskox close by, have dinner and finish the securing of recorded data for the day. After sitting in a plane all day, we all need to stretch our legs so we decide to take a run along the airstrip. Since there was a polar bear at the airfield last week, we are all on the lookout for something large and white that moves, thinking next time we should bring a flare gun…
Cover photo by Daniel Fridriksson